KR20230122049A - Manufacturing method of glass article - Google Patents

Abstract

After the molten glass Gm overflowing from the groove 8 of the molded body 3 flows down along the both side surfaces 10 of the molded body 3 by the overflow down-draw method, the lower end 3a of the molded body 3 A method for manufacturing a glass product comprising a molding step of forming a glass ribbon (Gr) by fusing in the molten glass (Gm) while containing an oxide containing yttrium, wherein the molded body (3) contains P ₂ O ₅ , In the molding step, the temperature difference (T1-T2) between the temperature T1 of the molten glass Gm in the groove portion 8 and the temperature T2 of the molten glass Gm in the lower end portion 3a is 100 ° C. below

Description

Manufacturing method of glass article

The present invention relates to a method of making a glass article.

In the manufacturing process of glass articles, such as a glass plate and a glass roll, molten glass is made to flow down along the surface of a molded object, and a glass ribbon is continuously formed by the overflow down-draw method, for example. After the molded glass ribbon is cooled to around room temperature while being conveyed downstream, it is cut every predetermined length to obtain a glass plate or wound into a roll shape to obtain a glass roll (see Patent Document 1, for example).

Japanese Unexamined Patent Publication No. 2018-062433

In the molded body, from the viewpoint of improving mechanical strength, a yttrium-containing oxide (for example, Y ₃ Al ₅ O ₁₂ , which is a composite oxide of yttrium and aluminum) may be added to the constituent components of the molded body.

As a result of intensive studies, the inventors of the present application and the like have found that when a glass ribbon containing P ₂ O ₅ is formed using a molded body containing an yttrium-containing oxide, yttrium oxide is eluted from the yttrium-containing oxide contained in the molded body in the molten glass. and so on, and came to discover for the first time the problem that devitrification occurs at the lower end of a molded body. Since devitrification derived from such an yttrium-containing oxide can become a defect in a glass ribbon and/or a glass article, it is important to reduce the generation amount also from the viewpoint of improving production efficiency or quality.

In addition, it is thought that the devitrification derived from a yttrium-containing oxide arises when yttrium oxide (Y ₂ O ₃ ) eluted in the molten glass from the yttrium-containing oxide, for example, reacts with P ₂ O ₅ in the molten glass. That is, it is considered that the devitrification product derived from the yttrium-containing oxide is, for example, a devitrification product (Y ₂ O ₃ -P ₂ O ₅ crystal) containing yttrium oxide and P ₂ O ₅ .

This invention makes it a subject to reliably reduce that the devitrification derived from the yttrium-containing oxide contained in a molded object generate|occur|produces, when shape|molding a glass ribbon using the overflow down-draw method.

(1) The present invention, devised in order to solve the above problems, by the overflow down-draw method, molten glass overflowing from the groove of a molded body flows down along both sides of the molded body, and then fuses at the lower end of the molded body to form a glass ribbon. A method for producing a glass product comprising a forming step wherein the molded body contains an oxide containing yttrium, the molten glass contains P ₂ O ₅ , and in the forming step, the molten glass in the groove portion and the molten glass in the lower end portion are formed. It is characterized in that the temperature difference of 100 ℃ or less.

In this way, even if yttrium oxide is eluted from the yttrium-containing oxide contained in the molded body into the molten glass, since the temperature difference between the groove of the molded body and the lower end of the molten glass is small, devitrification derived from the yttrium-containing oxide at the lower end of the molded body. (For example, devitrification containing yttrium oxide and P ₂ O ₅ ) can be suppressed from being generated.

(2) In the configuration of (1) above, it is preferable that the temperature of the molten glass in the groove portion is 1300°C or less.

Since it is suppressed that the viscosity of a molten glass becomes low too much by doing in this way, it becomes easy to shape|mold a glass ribbon from a molten glass.

(3) In the configuration of (1) or (2) above, it is preferable that the temperature of the molten glass at the lower end is 1100°C or higher.

Since it is suppressed that the viscosity of a molten glass becomes high too much by doing in this way, it becomes easy to shape|mold a glass ribbon from a molten glass.

(4) In the structures (1) to (3) above, the molten glass is a glass composition, in terms of mass%, SiO ₂ 40 to 70%, Al ₂ O ₃ 10 to 30%, B ₂ O ₃ 0 to 3% , Na ₂ O 5 to 25%, K ₂ O 0 to 5.5%, Li ₂ O 0.1 to 10%, MgO 0 to 5.5%, P ₂ O ₅ It is preferable to include 2 to 10%.

In this way, it becomes an aluminosilicate glass suitable for glass for chemical strengthening, and it becomes easy to achieve both ion exchange performance and devitrification resistance at a high level.

(5) In the structures of (1) to (4) above, it is preferable that the molten glass contains 0 to 1% by mass of MgO.

When the MgO content of the molten glass is high, a Mg-rich layer capable of suppressing the elution of yttrium oxide from the yttrium-containing oxide is formed on the surface of the molded body. The Mg-rich layer becomes, for example, a layer containing spinel (MgAl ₂ O ₄ ) as a main component when the formed body is an alumina-based refractory material. For this reason, it becomes difficult for yttrium oxide to elute into molten glass from the yttrium-containing oxide of a molded object. In contrast, when the MgO content of the molten glass is 1% by mass or less, it is difficult to form a Mg-rich layer on the surface of the molded body. For this reason, it becomes easy for yttrium oxide to elute in molten glass from the yttrium containing oxide of a molded object. Therefore, the effect of this invention becomes remarkable when MgO content of a molten glass is 1 mass % or less.

(6) In the structures (1) to (5) above, it is preferable that the molded body contains 1% by mass or more of the yttrium-containing oxide.

In this way, since yttrium oxide is easily eluted into the molten glass from the yttrium-containing oxide of the molded body, the effect of the present invention becomes remarkable.

ADVANTAGE OF THE INVENTION According to this invention, when shape|molding a glass ribbon using the overflow down-draw method, generation|occurrence|production of the devitrification derived from the yttrium containing oxide contained in a molded object can be reduced reliably.

1 is a side view of a manufacturing apparatus for carrying out a method for manufacturing a glass article according to an embodiment of the present invention.
Fig. 2 is a front view of a manufacturing apparatus for carrying out a method for manufacturing a glass article according to an embodiment of the present invention.
Fig. 3 is an enlarged side view showing the periphery of the molded body of Fig. 1;
4 is a longitudinal sectional view for explaining a heating test in an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on an accompanying drawing. In addition, in the orthogonal coordinate system composed of XYZ shown in the figure, the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction. In addition, the direction corresponding to the thickness direction of the width direction X and shape|molding of the width direction X and the direction corresponding to the width direction of the glass ribbon Gr shape|molding are called thickness direction Y.

1 to 3 are views showing a manufacturing apparatus 1 for realizing the method for manufacturing a glass article according to the present embodiment. As shown in the same figure, the manufacturing apparatus 1 is an apparatus for manufacturing glass plate G as a glass article by the overflow down-draw method, and the molding furnace 2 and the slow cooling furnace are sequentially formed from top to bottom. (4), a cooling chamber (5), and a cutting chamber (6) are provided. Between the forming furnace 2 and the slow cooling furnace 4, between the slow cooling furnace 4 and the cooling chamber 5, and between the cooling chamber 5 and the cutting chamber 6 are openings through which the glass ribbon Gr passes, respectively. It is partitioned by partition members (eg, the floor of a building) (eg, slit) (eg, slit) (F1, F2, F3).

The molding furnace 2 is a region for forming a glass ribbon Gr from the molten glass Gm by the overflow down-draw method. In the molding furnace 2, the molded body 3 for forming the glass ribbon Gr from the molten glass Gm and the both ends in the width direction X of the glass ribbon Gr molded into the molded body 3 are cooled. The 1st conveyance roller 7 is arrange|positioned.

The molded body 3 is formed of a long refractory material along the width direction X. As a refractory material, zircon, zirconia, alumina, magnesia, xenotime etc. are mentioned, for example.

At the top of the molded object 3, a groove portion (overflow groove) 8 formed along the width direction X is formed. A supply pipe 9 is connected to one end side of the groove portion 8 in the width direction X. Molten glass Gm is supplied into the groove part 8 through this supply pipe 9. The supply method of molten glass Gm is not limited to this. For example, you may make it supply molten glass Gm from both ends sides of the width direction X of the groove part 8, and you may make it supply molten glass Gm from above the groove part 8.

The molded body 3 has a symmetrical shape in the thickness direction Y. Both side surfaces 10 in the thickness direction Y of the molded body 3 are connected to the vertical surface portion 11 forming a plane shape along the vertical direction, and below the vertical surface portion 11, on a plane inclined with respect to the vertical direction. It is provided with an inclined surface portion 12 forming a. Each vertical surface portion 11 is a plane parallel to each other. Each inclined surface portion 12 is a plane inclined so as to approach each other in the thickness direction Y as it goes downward. That is, the molded body 3 forms a wedge shape tapering downward when viewed from the width direction X by forming each inclined surface portion 12, and the corner portion where each inclined surface portion 12 intersects is formed into a molded body ( It forms the lower end part 3a of 3). In addition, the shape of the vertical surface portion 11 may be changed to an inclined surface, a curved surface, or the like, or may be omitted.

The molded body 3 contains 1% by mass or more of a yttrium-containing oxide (eg, Y ₃ Al ₅ O ₁₂ which is a composite oxide of yttrium and aluminum) in order to ensure mechanical strength. In this embodiment, the molded body 3 is an alumina-based molded body containing yttrium-containing oxide. The alumina-based molded article preferably has an alumina (Al ₂ O ₃ ) content of 90 to 98% by mass and a content of yttrium-containing oxides of 2 to 10% by mass. In addition, the molded body 3 may be a zircon-based molded body or the like as described above. However, in the case of a zircon-based molded body, when molten glass (Gm) of a specific tempered glass composition flows down, zirconia derived from the molded body 3 is mixed into the molten glass (Gm), and the glass ribbon (Gr) and/or Or there exists a possibility of becoming a defect (a line shape defect etc.) of glass plate G. Therefore, from the viewpoint of preventing such defects due to zirconia, it is preferable that the molded body 3 is an alumina-based molded body.

Directly below the molded object 3, the 1st conveyance roller 7 is comprised as a roller pair which clamps each edge part of the width direction X of the glass ribbon Gr in the thickness direction Y. The first conveying roller 7 is a cantilever type roller and is always internally cooled in the molding process. The first conveying roller 7 is also called a cooling roller or an edge roller. Moreover, the 1st conveyance roller 7 may be provided in multiple stages (for example, two stages) in the vertical direction Z. For example, in the case of up and down two stages, it is preferable to use the 1st conveyance roller 7 of an upper stage as a driving roller, and using the 1st conveyance roller 7 of a lower stage as a free roller.

The slow cooling furnace 4 is a region for reducing the curvature and internal strain of the glass ribbon Gr. The internal space of the slow cooling furnace 4 has a predetermined|prescribed temperature gradient toward the downward direction. The temperature gradient of the internal space of the slow cooling furnace 4 can be adjusted with heating devices, such as a heater arrange|positioned on the inner wall of the slow cooling furnace 4, for example.

In the slow cooling furnace 4, the 2nd conveyance roller 13 is arrange|positioned. The second conveying roller 13 is also referred to as an annealing roller. The 2nd conveyance roller 13 is comprised as a roller pair which clamps each edge part of the width direction X of the glass ribbon Gr in the thickness direction Y. Although the 2nd conveyance roller 13 may be a double cantilever type roller arrange|positioned so that it may span the whole area of the width direction X of the glass ribbon Gr, it is a cantilever type roller in this embodiment. The second transport roller 13 is provided in a plurality of stages in the vertical direction Z.

The cooling chamber 5 is an area|region for cooling the glass ribbon Gr to room temperature vicinity. The cooling chamber 5 is open to the outside atmosphere at room temperature, and no heating device such as a heater is disposed.

In the cooling chamber 5, the 3rd conveyance roller 14 is arrange|positioned. The 3rd conveyance roller 14 is comprised as a roller pair which clamps each edge part of the width direction X of the glass ribbon Gr in the thickness direction Y. Although the 3rd conveyance roller 14 may be a double cantilever type roller arrange|positioned so that it may span the whole area of the width direction X of the glass ribbon Gr, it is a cantilever type roller in this embodiment. The third transport roller 14 is provided in a plurality of stages in the vertical direction Z.

Here, in the 2nd conveyance roller 13 and/or the 3rd conveyance roller 14, what does not pinch both ends of the width direction X of the glass ribbon Gr may be contained. That is, the opposing distance between the roller pairs constituting the 2nd conveyance roller 13 and/or the 3rd conveyance roller 14 is made larger than the thickness of both ends of the glass ribbon Gr in the width direction X, and the roller pair You may make it pass the glass ribbon Gr between them. Moreover, in this embodiment, both ends of the width direction X of the glass ribbon Gr obtained by the manufacturing apparatus 1 have a large thickness compared with the center part of the width direction X by the influence of shrinkage etc. of a molding process. It includes an edge part.

The cutting chamber 6 is a region for cutting the glass ribbon Gr into a predetermined size and obtaining a glass plate G as a glass article. In the cutting chamber 6, the cutting device (not shown) which cut|disconnects the glass ribbon Gr is arrange|positioned. In this embodiment, after forming a scribe line in the glass ribbon Gr, the cutting method of glass ribbon Gr by a cutting device is scribe cutting which bends along a scribe line and breaks, but it is not limited to this. The cutting method of the cutting device may be, for example, laser cutting or laser cutting.

The glass plate G is a glass original plate (mother glass plate) from which one or a plurality of product glass plates are sampled. The thickness of the product glass plate is, for example, 0.05 mm to 10 mm, and the size of the product glass plate is, for example, 700 mm x 700 mm to 3500 mm x 3500 mm. The product glass plate is used, for example, as a substrate or cover glass of a display. Further, the substrate or cover glass of the display is not limited to a flat panel, but may be a curved panel or a foldable panel.

As shown in FIG. 3, the manufacturing apparatus 1 has a first side heater 15 that heats the upper side of the molded object 3 outside the molding furnace 2, and a lower part of the side of the molded object 3. A second side heater 16 and a ceiling heater 17 for heating the uppermost part of the molded body 3 are further provided. The first side heater 15 is disposed on the upper outer wall of the side wall portion 2a of the molding furnace 2 . The second side heater 16 is disposed on the lower outer wall of the side wall portion 2a of the molding furnace 2 . The ceiling heater 17 is disposed on the outer wall of the ceiling portion 2b of the molding furnace 2.

In addition, the manufacturing apparatus 1 includes a first side thermometer 18 that measures the temperature of the side wall portion 2a at a position corresponding to the first side heater 15 outside the molding furnace 2, and a second A second side thermometer 19 measuring the temperature of the side wall 2a at a position corresponding to the side heater 16 and a ceiling thermometer measuring the temperature of the ceiling 2b at a position corresponding to the ceiling heater 17 (20) is further provided. In addition, the heaters 15, 16, and 17 may be divided into a plurality in the width direction X and constituted by a plurality of partial heaters. In this case, the thermometers 18, 19, and 20 may be provided for each partial heater.

Next, the manufacturing method of the glass article according to this embodiment is demonstrated.

As shown in FIGS. 1-3, this manufacturing method includes a molding process, a slow cooling process, and a cutting process. Each of these steps is performed using the manufacturing apparatus 1 described above.

In the molding process, molten glass Gm is supplied to the groove 8 of the molded object 3 in the molding furnace 2, and the molten glass Gm overflowing from the groove 8 on both sides is separated into each vertical surface portion. (11) and along the inclined surface portion 12, it flows down and joins again at the lower end portion 3a. Thereby, the belt-shaped glass ribbon Gr is continuously formed from the molten glass Gm.

The molten glass (Gm) is an aluminosilicate glass containing P ₂ O ₅ . Specifically, the molten glass (Gm) is a glass composition, in terms of mass%, SiO ₂ 40 to 70%, Al ₂ O ₃ 10 to 30%, B ₂ O ₃ 0 to 3%, Na ₂ O 5 to 25%, It is preferable to include 0 to 5.5% of K ₂ O, 0.1 to 10% of Li ₂ O, 0 to 5.5% of MgO, and 2 to 10% of P ₂ O ₅ . When the glass composition range is regulated in this way, it becomes easy to achieve both ion exchange performance and devitrification resistance at a high level in the glass ribbon Gr. For this reason, a glass ribbon Gr (glass plate G) suitable for a glass plate for chemical strengthening used for cover glasses such as mobile phones, digital cameras, PDAs (portable terminals), and touch panel displays is obtained.

MgO is a component that lowers the high-temperature viscosity, improves the meltability and moldability, and increases the strain point and Young's modulus, and among alkaline earth metal oxides, it is a component with a great effect of enhancing ion exchange performance. However, when the content of MgO is too large, the density and thermal expansion coefficient tend to increase, and the glass tends to devitrify. Therefore, suitable upper ranges of MgO are 5.5% by mass or less and 4% by mass or less. Here, when the content of MgO is 0 to 1% by mass, it is difficult to form a Mg-rich layer that functions as a diffusion suppressing layer of the yttrium-containing oxide on the surface of the molded body 3, so the temperature of the molten glass (Gm) described later management becomes particularly important.

P ₂ O ₅ is a component that enhances ion exchange performance when glass is chemically strengthened, and in particular, is a component that increases the stress depth of a compressive stress layer. Moreover, as the content of P ₂ O ₅ increases, the glass becomes easier to phase-separate. The lower limit of P ₂ O ₅ is preferably 2% by mass or more, more preferably 4% by mass or more. On the other hand, the upper limit of P ₂ O ₅ is preferably 10% by mass or less, more preferably 9.5% by mass or less, and still more preferably 9% by mass or less.

Li ₂ O is an ion exchange component and is also a component that lowers the high-temperature viscosity and improves the meltability and formability. Moreover, it is a component which raises a Young's modulus. In addition, Li ₂ O is also a component that is eluted during ion exchange treatment and deteriorates the ion exchange solution. Therefore, a suitable lower range of Li ₂ O is 0.1% or more, 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, particularly 2.5% or more, in mass%, and a suitable upper limit range is 10% or less, 8% or less. or less, 5% or less, 4.5% or less, 4.0% or less, particularly less than 3.5%.

In the molding step, the temperature T1 of the molten glass Gm in the groove 8 of the molded object 3 and the temperature T2 of the molten glass Gm in the lower end 3a of the molded object 3 The temperature difference (T1-T2) of is controlled to 100°C or less. The temperature difference (T1-T2) is preferably 90°C or less, 80°C or less, particularly 70°C or less. In this way, even if yttrium oxide is eluted from the yttrium-containing oxide contained in the molded body 3 in the molten glass Gm, since the temperature difference (T1-T2) of the molten glass Gm is small, the lower end of the molded body 3 In (3a), generation of devitrification (for example, Y ₂ O ₃ -P ₂ O ₅ crystals) derived from the yttrium-containing oxide can be suppressed. That is, since it is possible to suppress generation of defects caused by devitrification derived from yttrium-containing oxides in the glass ribbon Gr or the glass plate G, the production efficiency and quality can be improved. In addition, the lower limit of the temperature difference (T1-T2) of molten glass Gm can be 0 degreeC or more, for example.

The temperature T1 of the molten glass Gm in the groove portion 8 of the molded body 3 is preferably 1300°C or lower, 1250°C or lower, particularly 1220°C or lower. Since it is suppressed that the viscosity of molten glass Gm becomes low too much if it does in this way, it becomes easy to shape|mold the glass ribbon Gr from molten glass Gm. In addition, when the temperature T1 is 1220° C. or less, since the elution amount of yttrium oxide itself from the yttrium-containing oxide of the molded body 3 can be significantly reduced, devitrification derived from the yttrium-containing oxide can be more reliably suppressed. can

The temperature T2 of the molten glass Gm at the lower end 3a of the molded body 3 is preferably 1130°C or higher, 1150°C or higher, and particularly 1180°C or higher. Since it is suppressed that the viscosity of molten glass Gm becomes high too much if it does in this way, it becomes easy to shape|mold the glass ribbon Gr from molten glass Gm. In addition, since the temperature T2 is relatively high, it becomes easy to control the temperature difference (T1-T2) to 100°C or less.

The temperature T1 of the molten glass Gm in the groove part 8 of the molded body 3, the temperature T2 of the molten glass Gm in the lower end 3a of the molded body 3, and the temperature difference ( T1-T2) can be adjusted by the heaters 15-17, for example. In addition, the temperatures T1 and T2 can be estimated from the furnace wall temperatures of the molding furnace 2 measured with, for example, radiation thermometers or thermometers 18 to 20.

The time required from when the molten glass Gm flows through the groove 8 of the molded body 3 to passing through the lower end 3a of the molded body 3 is, for example, 10 to 600 seconds, 60 to 300 Seconds are more preferred.

At a slow cooling process, in the slow cooling furnace 4, the glass ribbon Gr shape|molded by the formation process is cooled slowly.

At a cooling process, the glass ribbon Gr cooled by the slow cooling process in the cooling chamber 5 is cooled to near room temperature.

At a cutting process, in the cutting chamber 6, glass ribbon Gr cooled at the cooling process is cut|disconnected and glass plate G is obtained. The cutting process cuts and removes the 1st cutting process which cuts the glass ribbon Gr in the width direction X for every predetermined length, and obtains the glass plate G, and the edge part of both ends of the width direction X of the glass plate G It includes a second cutting process to do.

In addition, the post-process of a cutting process is not specifically limited, For example, the cutting-out process which cuts out the glass plate of a desired size from glass plate G by cutting, an edge processing process, a washing process, an inspection process, a packaging process, A chemical strengthening step or the like may be included. In the inspection step, it is preferable to inspect whether the glass plate G contains devitrification derived from the yttrium-containing oxide.

Although the glass article manufacturing apparatus and manufacturing method thereof according to the embodiment of the present invention have been described, the embodiment of the present invention is not limited to this, and various changes may be made without departing from the gist of the present invention. possible.

In the above embodiment, the case where the glass product is glass plate G has been described, but the glass product may be, for example, a glass roll obtained by winding a glass ribbon Gr in a roll shape.

In the said embodiment, although the case where molten glass Gm was aluminosilicate glass was illustrated, molten glass Gm may be glass containing _P2O5 other than aluminosilicate glass _.

Example

Hereinafter, examples according to the present invention will be described, but the present invention is not limited to these examples.

As shown in Fig. 4, as the test body 101 of the comparative test of Examples 1 and 2 and Comparative Example, a molten glass 102 was placed on a refractory material 103, and both 102 and 103 were brought into contact with each other. prepared The molten glass 101 is an aluminosilicate glass containing molten glass (Gm), P ₂ O ₅ (8.7% by mass) and MgO (0.1% by mass) of a copper material, and the refractory material 103 is a mixture of a molded body and a copper material. It is a rod-shaped alumina-based refractory material containing yttrium-containing oxide (3% by mass). That is, the contact part of the molten glass Gm flowing down the surface of the molded object 3 and the molded object 3 is reproduced by the contact part of the molten glass 102 and the refractory material 103. In addition, the configuration of the test body 101 is common to Examples 1 and 2 and Comparative Example.

A heating test was conducted in which each test body 101 of Examples 1 and 2 and Comparative Example was heated within an electric furnace 104 having a heater 104a. In the heating test, after heating the test body 101 at a relatively high-temperature first temperature that reproduces the temperature of the molten glass (Gm) in the groove portion 8 of the molded body 3, the lower end of the molded body 3 ( The test body 101 was heated at the relatively low temperature 2nd temperature which reproduced the temperature of the molten glass Gm in 3a). In addition, although each temperature shown below is the atmospheric temperature of the electric furnace 104, the temperature of the molten glass 102 can also be regarded as the same temperature.

(1) Example 1

In Example 1, after heating the test body 101 at 1250°C for 72 hours in the electric furnace 104, it was heated at 1180°C for 48 hours. 1250 degreeC is the 1st temperature which reproduced the temperature of the molten glass (Gm) in the groove part 8 of the molded object 3, and 1180 degreeC is the molten glass (Gm) in the lower end part 3a of the molded object 3 It is the second temperature that reproduces the temperature of That is, in Example 1, the temperature difference (T1-T2) is 70°C obtained by subtracting the second temperature from the first temperature. In addition, the reason why the heating time at the first temperature (1250 ° C.) is longer than the heating time at the second temperature (1180 ° C.) is to ensure sufficient time for yttrium oxide to elute from the yttrium-containing oxide of the refractory (formed body) 103. It is for Also in Example 2 and Comparative Example, the heating time at the first temperature is longer than the heating time at the second temperature for the same reason.

(2) Example 2

In Example 2, after heating the test body 101 at 1220°C for 72 hours in the electric furnace 104, it was heated at 1150°C for 48 hours. 1220 degreeC is the 1st temperature which reproduced the temperature of the molten glass (Gm) in the groove part 8 of the molded object 3, and 1150 degreeC is the molten glass (Gm) in the lower end part 3a of the molded object 3 It is the second temperature that reproduces the temperature of That is, in Example 2, the temperature difference (T1-T2) is 70°C.

(3) Comparative Example

In the comparative example, after heating the test body 101 at 1250°C for 72 hours in the electric furnace 104, it was heated at 1120°C for 48 hours. 1250 degreeC is the 1st temperature which reproduced the temperature of the molten glass (Gm) in the groove part 8 of the molded object 3, and 1120 degreeC is the molten glass (Gm) in the lower end part 3a of the molded object 3 It is the second temperature that reproduces the temperature of That is, in the comparative example, the temperature difference (T1-T2) is 130°C.

And after each molten glass 102 which passed through the above heating test was cooled to room temperature, the substance in each glass obtained by cooling was confirmed by the SEM image, and the substance found thereafter was derived from the yttrium-containing oxide by EPMA. It was confirmed whether or not it was a devitrifying substance (Y ₂ O ₃ -P ₂ O ₅ crystal). As a result, in Example 1 and Example 2 in which the temperature difference (T1-T2) was 100°C or less, devitrification derived from the yttrium-containing oxide was not confirmed in the glass in which the molten glass 102 was cooled. On the other hand, in the comparative example in which the temperature difference (T1-T2) is more than 100 degreeC, devitrification derived from the yttrium-containing oxide was confirmed in the glass which cooled the molten glass 102.

Based on the test results of Example 1, while setting the temperature of the molten glass (Gm) in the groove part 8 of the molded object 3 to 1220 ° C. in the molding process, at the lower end 3a of the molded object 3 The glass ribbon Gr was shape|molded by setting the temperature of the molten glass Gm in 1150 degreeC. At that time, the time required until the molten glass Gm passed through the lower end 3a of the molded object 3 after overflowing the groove part 8 of the molded object 3 was about 300 seconds. As a result, devitrification derived from the yttrium-containing oxide was not observed in the obtained glass plate (G).

Based on the test results of Example 2, while setting the temperature of the molten glass (Gm) in the groove portion 8 of the molded body 3 to 1250 ° C. in the forming process, at the lower end 3a of the molded body 3 The glass ribbon Gr was shape|molded by setting the temperature of the molten glass Gm in 1180 degreeC. At that time, the time required until the molten glass Gm passed through the lower end 3a of the molded object 3 after overflowing the groove part 8 of the molded object 3 was about 300 seconds. As a result, devitrification derived from the yttrium-containing oxide was not observed in the obtained glass plate (G).

Based on the test results of the comparative example, while setting the temperature of the molten glass Gm in the groove part 8 of the molded object 3 to 1250 ° C. in the molding process, in the lower end 3a of the molded object 3 The glass ribbon Gr was shape|molded by setting the temperature of the molten glass Gm to 1120 degreeC. At that time, the time required until the molten glass Gm passed through the lower end 3a of the molded object 3 after overflowing the groove part 8 of the molded object 3 was about 300 seconds. As a result, devitrification derived from the yttrium-containing oxide was confirmed on a part of the obtained glass plate G.

From the above, the temperature T1 of the molten glass Gm in the groove part 8 of the molded object 3 and the temperature T2 of the molten glass Gm in the lower end 3a of the molded object 3 It has been recognized that devitrification derived from the yttrium-containing oxide can be suppressed by controlling the temperature difference (T1-T2) to 100°C or less.

Further, in the comparative example, the temperature T1 of the molten glass Gm in the groove portion 8 of the molded body 3 was 1250° C., and devitrification derived from yttrium-containing oxide occurred in a part of the glass plate G obtained. did. Similar to this comparative example, since Example 2 sets the temperature T1 of the molten glass Gm in the groove part 8 of the molded object 3 to 1250 degreeC, the molten glass Gm of Example 2 is compared It is estimated that the same amount of yttrium oxide as in the example was eluted. In Example 2, the temperature T2 of the molten glass Gm at the lower end 3a of the molded body 3 is increased to 1180 ° C., and the temperature difference (T1-T2) is made smaller than in the comparative example, thereby devitrifying the yttrium oxide. is presumed to have been prevented.

In Example 1, the temperature T1 of the molten glass Gm in the groove 8 of the molded body 3 was lowered to 1220 ° C. than in Comparative Example and Example 2. It is estimated that the elution of yttrium oxide is reduced. For this reason, in Example 1, even if the temperature T2 of the molten glass Gm in the lower end 3a of the molded body 3 is lowered than in Example 2 to 1150°C, the temperature difference (T1-T2) is maintained. It is presumed that the devitrification of yttrium oxide could be prevented.

DESCRIPTION OF SYMBOLS 1: Glass article manufacturing apparatus 2: Molding furnace
3: molded body 3a: lower part
4: slow cooling furnace 5: cooling chamber
6: cutting chamber 7: first conveying roller
8: groove 9: supply pipe
13: 2nd conveying roller 14: 3rd conveying roller
15: first side heater 16: second side heater
17: ceiling heater 18: first side thermometer
19: second side thermometer 20: ceiling thermometer
G: glass plate Gm: molten glass
Gr: glass ribbon

Claims (6)

A method for manufacturing a glass article comprising a forming step of forming a glass ribbon by allowing molten glass overflowing from a groove of a molded body to flow down along both side surfaces of the molded body by an overflow down-draw method and then fusing at the lower end of the molded body to form a glass ribbon. ,
The molded body contains an oxide containing yttrium, and the molten glass contains P ₂ O ₅ ,
In the forming step, a temperature difference between the molten glass in the groove portion and the molten glass in the lower end portion is 100° C. or less. According to claim 1,
The manufacturing method of the glass article whose temperature of the said molten glass in the said groove part is 1300 degreeC or less. According to claim 1 or 2,
The manufacturing method of the glass article whose temperature of the said molten glass in the said lower end part is 1100 degreeC or more. According to any one of claims 1 to 3,
The molten glass has a glass composition, in terms of mass%, SiO ₂ 40-70%, Al ₂ O ₃ 10-30%, B ₂ O ₃ 0-3%, Na ₂ O 5-25%, K ₂ O 0-5.5 %, Li ₂ O 0.1 to 10%, MgO 0 to 5.5%, P ₂ O ₅ A method for producing a glass article containing 2 to 10%. According to any one of claims 1 to 4,
The manufacturing method of the glass article in which the said molten glass contains 0-1 mass % of MgO. According to any one of claims 1 to 5,
The method for producing a glass article according to claim 1, wherein the formed body contains 1% by mass or more of yttrium-containing oxide.